Funding for the assistants - who ministers believe have been a key factor in raising primary literacy and numeracy standards - had previously only been guaranteed until the end of March 2002.
The announcement comes after a highly controversial move by Birmingham's education chief Tim Brighouse. He advised headteachers in the city to use assistants to cover for absent staff in the short term.
At least five schools in the city have done so, prompting criticism from the unions and from TES readers who contacted our websit.
Bethan Lydiard, a qualified nursery nurse and final year BEd student from Swansea, told The TES that assistants were not trained as teachers and should "definitely not be used as substitutes".
She said: "While training as a nursery nurse I was taught nothing about the national curriculum. It is only as a student teacher that I have been and can apply it effectively."
But Helen Slater of Dudley said assistants should be able to cover for teachers.
She said: "It's got to be a good thing for pupils to be taught by someone they know and trust and, of course, assistants do know the capabilities of the children."